Biology Chapter on DNA and Chromosomes

DNA and Chromosomes

• DNA is the genetic code
• Chromosomes are structures made of tightly packed DNA and proteins, organizing the DNA into manageable units.
• DNA is stored in the nucleus.
• mRNA copies the DNA code (transcription) and carries it to the cytoplasm, where ribosomes read it (translation).

DNA Structure and Function

• DNA is a code for making proteins, the building blocks of cells and controllers of bodily functions.
• DNA polymerase builds new DNA strands, ensuring accurate DNA copies before cell division.
• RNA polymerase builds RNA from a DNA template, making RNA that carries the genetic code for protein assembly.
• DNA is double-stranded, uses thymine, and stays in the nucleus.

RNA Structure and Function

• RNA is single-stranded, uses uracil, and moves to the cytoplasm.
• mRNA carries the DNA's instructions to the ribosomes in the cytoplasm for protein synthesis.
• tRNA brings amino acids to the ribosome during translation.

Mitosis vs. Meiosis

• Mitosis produces 2 identical cells for growth and repair, and is a 1-cycle process producing diploid cells.
• Meiosis produces 4 unique cells for reproduction (sperm/egg), and is a 2-cycle process producing haploid cells.
• Meiosis involves homologous chromosome pairing and recombination (crossing over), which is absent in mitosis.

Vocabulary

• Autotroph: Organism that makes its own food.
• Heterotroph: Organism that cannot make its own food and consumes other organisms.
• Histones: Proteins that pack and organize DNA.
• Haploid: Cell with half the usual number of chromosomes.
• Diploid: Cell with two sets of chromosomes (one from each parent).
• Mitochondria: Produces energy for the cell via cellular respiration.
• DNA Polymerase: Enzyme that copies DNA.
• RNA Polymerase: Enzyme that makes RNA from a DNA template.
• Homolog: Similar chromosomes from each parent that pair during meiosis.
• Ortholog: Similar genes in different species from a common ancestor.

Key Cellular Processes

• Transcription: DNA to mRNA (nucleus)
• Translation: mRNA to protein (ribosome)
• Genetic Recombination: Process of DNA exchange between homologous chromosomes, increasing genetic diversity.
• Gene: Segment of DNA providing instructions for a protein.
• Genome: Complete set of an organism's DNA.
• Genotype: Genetic makeup, combination of alleles.
• Ribosome: Cell structure that builds proteins by reading mRNA and linking amino acids.
• Allele: Version of a gene.
• Homozygous: Two identical alleles.
• Heterozygous: Two different alleles.
• Nucleus: Cell control center housing DNA.
• Zygote: Fertilized egg.

Punnett Square

(No further elaboration given)